How do I change the Unity Hub theme?

Symptoms:

• How do I change the Hub to the light theme?
• How do I change the Hub to the dark theme?
• How do I sync the Hub's appearance to my system's settings?

Cause:

With the release of Hub version 3.4.0, users can change how the Hub looks on their machine.

Resolution:

To alter the appearance of the Unity Hub, please follow the below steps:

1. Launch the Unity Hub.
2. Click Preferences (cog icon).
   
3. Click Appearance.
   
4. From this screen, you can select Light, Dark, or Automatically sync with system settings (Changes apply immediately).
   

More information:

How can I change my Editor theme?

What is the Unity Hub?

How do I download Unity?